Image-Guided Radiotherapy of Lung Cancer PDF

Preface

Lung cancer is the leading cause of cancer death in the United States and the world. The five-year survival rate for all lung cancer patients over the past 20 years was around 15%. Approximately 15-20% of non-small cell lung cancer (NSCLC) patients present with stage I/II disease that is considered surgically resectable. However, most patients present with locally advanced disease requiring combined modality treatment including radiotherapy. In addition, patients with stage I/II NSCLC who cannot tolerate surgical resection due to co-morbidity are treated with definitive radiotherapy. For conventional radiotherapy, local control has been reported to be around 30-50% for stage I/II disease and 30% for stage III. Uncontrolled loco-regional disease is a major source for continuous seeding to distant organs and causes eventual treatment failure and cancer death. Eradication of loco-regional disease is an essential step for cure. There are three main reasons for local failure after radiotherapy: 1) geographic misses due to inadequacy of imaging tools for staging and radiotherapy planning; 2) respiratory tumor motion during radiotherapy; and 3) inadequate radiation dose due to concerns of significant toxicity. Novel approaches to improve radiotherapy in lung cancer are urgently needed.

The recent development of image-guided radiotherapy (IGRT) has introduced a new era of radiotherapy for lung cancer. PET/CT has been shown to improve targeting accuracy in 25-50% of cases, and 4-dimensional CT scanning has helped to individualize patients' radiotherapy based on tumor motion. Intensity modulated radiation therapy (IMRT) may allow us to escalate radiotherapy dose without increasing toxicity. Stereotactic body radiation therapy (SBRT) has opened the door to achieving higher than 90% local control by focused, hypofractionated, high biologically equivalent dose of radiotherapy. Proton radiotherapy may hold promise for lung cancer due to its physical characteristics that lead to high and conformal dose distribution in the tumor while reducing the entrance dose and stopping the beam distal to the target. These novel approaches were considered experimental just a couple of years ago. However, because of the potentially significant improvement in clinical outcome and accumulating clinical data, they are beginning to become standard treatment for lung cancer at major cancer centers.

In this book, we focus on novel approaches using IGRT, particularly PET/CT, 4-D CT, gated radiotherapy, stereotactic body radiation therapy, IMRT, and proton radiotherapy in lung cancer. We provide our recommended dose, fractionation, target volume delineation, treatment techniques, and normal tissue tolerances. Our intention is to provide disease stagespecific treatment guidelines and step-by-step techniques so that radiation oncologists may incorporate these new techniques into their clinical practice.